<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<!-- 写在head里面 -->
<script type="text/javascript">
	alert("头部");
</script>
<!-- 外部引入的.js文件 -->
<script type="text/javascript" src="my.js"></script>
</head>
<body>
<!-- 写在body里面 -->
<script type="text/javascript">
	alert("身体");
</script>
</body>
</html>